The invention relates to an airbag module.
Known airbag modules comprise an airbag and a front cover which is made of plastic and has a middle part and, surrounding the middle part, a predefined outlet opening for the airbag, the opening in the closed state being surrounded by a ring-shaped part of the cover, the ring-shaped part being removed to free the outlet opening when the airbag is unfolded, and the middle part being attached to the module in such a way that, when the airbag unfolds, the middle part is prevented from moving freely.
Such an airbag module is known from DE 197 49 914 A. There, an airbag is provided which in the inflated state has a front that faces the vehicle occupant and continues into a centered indentation that is formed in that a middle airbag part is prevented from moving freely out of the module. In this manner, a gas-filled chamber surrounding the indentation is formed. The middle part of the cover remains in place when the cover is opened, that is to say, it is not swiveled or moved towards outside. The important aspect of an airbag module with a stationary middle part is that it is held very firmly and securely on the rest of the module when the outlet opening is freed.
The invention provides an airbag module with which the cover may be designed to be lightweight but nevertheless very sturdy.
According to the invention, an airbag module comprises an airbag and a front cover which is made of plastic. The front cover has a middle part and, surrounding the middle part, a predefined outlet opening for the airbag. In the closed state of the cover, the opening is surrounded by a ring-shaped part of the cover. The ring-shaped part is removed to free the outlet opening when the airbag is unfolded. The middle part is attached to the module in such a way that, when the airbag unfolds, the middle part is prevented from moving freely. The module further comprises a reinforcement ring which is embedded in the middle part and runs adjacent and along an inner edge of the ring-shaped part of the cover and attaches the middle part to the module, preventing it from moving freely when the airbag unfolds. The reinforcement ring, which is preferably a sheet metal ring, prevents the plastic from tearing out in the area of the middle part in the area of its attachment on the module side when the airbag unfolds. The reinforcement ring, which should be rigidly attached on the module side, holds the middle part back when the cover is opened. Due to the relatively large surface area of the ring, there is no risk of the plastic tearing out, in comparison, for example, to a screw embedded in the plastic. Moreover, the ring is provided on the outer edge of the middle part, that is to say, exactly in the area in which the transition to the ring-shaped part is provided, and in which, when the cover is supposed to tear open, there is also a high load on the cover. In this context, the reinforcement ring prevents the cover from tearing open any further. Since a reinforcement ring rather than a disk is provided, a considerable amount of material and thus weight can be saved, especially since the reinforcement ring, as already mentioned, is normally made of sheet metal.
It is more and more often the case that sophisticated-looking emblems made of metal or enameled metal are being placed on the cover by the manufacturers. These emblems are separate parts that have to be attached to the cover. One embodiment of the invention provides that the emblem, which is made as a separate part, has at least one attachment projection on the rear side, which extends through the middle part as well as radially inwards with respect to the reinforcement ring. This means that the emblem is not attached directly to the ring but rather that it extends through the hole in the ring and through the plastic situated therein. So far, the idea has been to attach emblems, for example, directly to inserted metal plates or to counterplates that lie against the rear side of the cover. However, in the case at hand here, this would mean that the reinforcement ring would have to be configured wider radially inwards, which would come at the expense of the weight. The preferred embodiment provides that the reinforcement ring is not provided for this purpose and consequently can be configured more narrowly. However, since the reinforcement ring surrounds the attachment projection, there is no risk that the middle part of the cover will tear in the area of the attachment projection when the outlet opening is opened, thereby weakening the attachment of the emblem. Therefore, the reinforcement ring surrounds the attachment projection without being directly connected to it, somewhat like a protective wall.
Moreover, according to a preferred embodiment, the attachment projection is bent on the rear side of the middle part, i.e. the emblem is only attached to the plastic, so that no separate additional parts are needed for attachment purposes.
In another embodiment, there is provided a pot-shaped diffuser in the module, the front wall of the diffuser extending to the middle part of the cover. On the one hand, the reinforcement ring can be attached to the diffuser and on the other hand, as an alternative or additionally, the attachment projection can protrude through an opening in the diffuser, in order to be bent on the rear side so as to create a form-fitting connection between the diffuser and the emblem.
Preferably, the airbag is an annular chamber airbag of the type mentioned above. In the inflated state, it has a front facing the vehicle occupant and this front continues into a centered indentation. The latter is formed in that a middle airbag part that runs on the rear side of the middle section is prevented from moving freely out of the module. In this context, the indentation does not create a chamber filled with the gas that is blown in.
Preferably, the middle airbag part is attached to the module by the attachment of the reinforcement ring to the module and is prevented from moving freely when the airbag unfolds. Therefore, the reinforcement ring has a dual function since, on the one hand, it prevents the middle part of the cover and, on the other hand, the middle airbag part from moving freely out of the module.